Before the present invention, the erection of forms in the interior of an elevator shaft, stairway shaft and the like was cumbersome and time consuming. One way to position the forms was to erect a semi-permanent super structure under the forms at each floor level until the walls for that level were formed and then build additional super structure on top of the original super structure to get up to the next floor and so on. An alternative method was to erect the forms on a vertically movable platform which could be raised by a suitable hoist. However, it was difficult to properly anchor this platform which was suspended by a cable or chain and to properly level and immobilize the interior forms during the concrete pouring operation. In order to do the job properly, many man hours were required and even then sometimes the results were less than totally satisfactory. Also, there were difficulties in forming the inside corners so that the forms could be retracted after the concrete was poured and set.